For me it’s been more about making practice parts instead of aiming for building the entire instrument with the practice wood. At least so far. I initially had the mindset that I would build the whole thing once with practice wood and then start working on the real thing. The book explains each step so it seems simple in theory. But it is not simple if you are a beginner like me. My focus now is on practicing and learning instead, and the parts will be finished when they’re finished.
In addition to practice parts I recommend using random practice blanks here and there. This is to get lots of practice on difficult things such as joints - without having to remake the entire Sao etc if you mess up.
There will be lots and lots of mistakes so don’t get discouraged.This is how we humans learn. Inventors and geniuses all have one thing in common and it is the ocean of mistakes that lead up to the success. Anyone who doesn’t give up can achieve great feats in my opinion. Each mistake teaches you something you didn’t know before, and then you’ll figure out how to avoid it in the future. If you think about the fact that you will keep these skills for rest of your life after learning them it will not feel like a waste of time. But make sure to read ahead in the book also, to ensure your new found “solutions” do not mess up something for later.
Be prepared to invest a lot of time. You have to enjoy the journey more than the result. Woodworking will become one of your main hobbies. That is not optional 
Even practice parts take time. Rushing or being sloppy is a recipe for failure which will just end up wasting your time more. Once I realized that this project will take an undetermined amount of time from my life and that I still enjoy the journey I stopped rushing altogether. You might even get the urge to do unrelated side projects from time to time. Remember, woodworking will be one of your main hobbies (if you decide to do this). A shamisen is big and complicated project. Each part is as complicated as a smaller side project - but probably won’t give the same level of satisfaction as finishing a small project, like a nice wooden box or something.
Glue can fix lots of mistakes and it’s probably better to fix things instead of starting over whenever you can.
Soft wood is good when you’re practicing because it’s much easier to work with than hard wood. I use pine since it’s also the cheapest wood where I live. But you will also have to learn how to sharpen your planes and chisels properly so they can cut hard wood later. A dull tool requires a lot of force to use and that leads to randomness and crappy results.
If you have access to a good table saw you can make joint work much easier. But if you are a beginner you must have someone experienced guide you. Table saws are unforgiving and can cause terrifying injuries in the blink of an eye.
Some parts require 45 degree cuts that are near flawless. It can be done by hand tools too but not freehand (unless you’re a pro). So a cheap hand-operated mitre saw has worked great for me. A table saw will give the best results though.
Regarding your choice of wood. Oak might be hard enough for the neck/Sao if you glue several long pieces in parallel to strengthen it, or if you make a 3-piece Sao (difficult). Or maybe use a truss rod but I don’t think the book explains how to do that. Oak is much softer than what’s traditionally used for Sao. Same with maple. The cheapest wood fit for a Sao I have found though is Jatoba. It is extremely hard, feels like it’s made of bricks basically. And it’s one of the cheaper exotic hardwoods. When the book was written African Padauk was recommended, but these days I’m not able to get ahold of it anymore in my part of the world. You can use softer wood for the Dou/body if you want. Cherry and Walnut are relatively soft woods. You could also look up guitar tone woods and listen to how they sound if you want. Kyle doesn’t think the wood type makes much difference to the sound of a Shamisen though.
